Bill Gates Sr. is in his element working on unglamorous projects in a group. Here, he hammers out details of the Washington State Tax Structure Study in a windowless conference room in SeaTac.

FOR A GUY who towers a head taller than everyone else, has an intellect that digests information more voraciously than a recycling truck, and also happens to be the father of the world's richest man, William H. Gates Sr. is remarkably down-to-earth.

He eats bacon with his fingers off a plastic tray at Burgermaster. He delves, with delight, into the semantics of Chapter 4b in a draft of the Washington State Tax Structure Study Committee. He listens with an open mind whether ideas come from a local teen mom or President Jimmy Carter. He gets impatient when voices aren't loud enough for his 77-year-old ears to hear.

The elder Gates has few pretensions, but that doesn't mean he isn't imposing. He stands 6 feet 6 inches in size 14 tasseled loafers and a gray suit, size 48. ("I have many dimensions," he says, "all of them excessive.") The retired attorney is witty without being jocular. His speech is as precise as his starched button-down shirts. Even in casual conversation, if you could call it that, he doesn't so much chat as elocute.

"My dad's a very thoughtful person, and things that should be dealt with seriously, he deals with seriously and you listen," says Microsoft Chairman Bill Gates, who grew up in Seattle's View Ridge neighborhood, the middle of three children.

"It was one thing to have Mom upset, but when Dad's upset, you just don't mess around. I was a kid willing to cause trouble and break any rules, but if Dad was intent on something, you just didn't think twice about crossing him. He had this quality of energetic leadership. He conveyed, somehow, without being too explicit, his high expectations of us. There was a certain gravitas to his statements."

"Inspiration, Unh!" Gates Sr. joins a cheer with the local chapter of City Year, a youth-service program the Bill & Melinda Gates Foundation helps fund. Earlier, Gates Sr. chatted with the young people about education, foreign aid, drugs, making mistakes. The retired attorney doesn't talk down to people, using the same demeanor and level of discussion no matter who they are.

BILL'S DAD is the co-chair and CEO of the Bill & Melinda Gates Foundation which, with an endowment of $24 billion, is the largest philanthropy in world history.

"I never imagined this young and argumentative fellow who was eating my food and using my name would be my future employer," the elder Gates quipped during a speech to the Seattle Rotary Club.

In his understated way, Gates Sr. describes how the Foundation started soon after the death of Mary Gates, his wife of 44 years: "Bill and Melinda were having a good deal of trouble dealing with all the requests they got for support of one kind or another, and they were not terribly responsive. They were busy with family and his business . . . He had pretty uniformly resisted (starting a foundation) because he didn't want another administrative burden . . . At that point, Mary had died and my law practice was winding down and I felt like I had some time. I suggested they could just send me the mail and I would expedite the responses. They thought that was a really good idea."

While visiting a clinic in South Africa last spring, Gates Sr., Nobel Peace Laureate Nelson Mandela and President Jimmy Carter hold healthy babies whose mothers were treated with Nevirapine, an inexpensive drug that helps prevent transmission of the AIDS virus from mother to child. Gates Sr. thinks people with resources have a responsibility to help those without. The Gates Foundation has committed more than $3 billion to global health.

It was January, 1995. In the rec room of his Laurelhurst home, Gates Sr. sorted mail. His occasional business lunches at the nearby Burgermaster inspired grant seekers to mail requests to him there. Within a few years, the elder Gates' efforts in philanthropy and global health merged with an earlier Gates technology-in-libraries initiative run by retired Microsoft executive Patty Stonesifer.

The Foundation has since committed to grants of nearly $6 billion, including $452 million for Pacific Northwest projects. Gates Sr. takes a special interest in local giving, in part because of his long history as a leader of King County United Way, Greater Seattle Chamber of Commerce, University of Washington Board of Regents and two dozen other Northwest groups. Gates Sr. also has decades of legal experience as a senior partner of Preston, Gates & Ellis and president of both the Seattle/King County and the Washington State Bar Associations. Under his leadership, equal justice for the poor and disadvantaged became a goal of the state group, spurring public and private funding for legal aid for the poor and in 1999 prompting the state Supreme Court to create an Access to Justice Board, now a national model.

Foundation president Stonesifer says Gates shares his son's "impatience with fuzzy thinking, a real eagerness to get to the meat of the matter, the way they pull apart issues and problems. What stands out about Bill Sr. is his decades using these skills as a statesman."

Rather than patching a problem, she says, his approach is to tackle its root.

Bill Gates and his dad talk about the family's Thanksgiving plans after a meeting at the Gates Foundation. Father and son share "an impatience with fuzzy thinking, a real eagerness to get to the meat of the matter, the way they pull apart issues and problems," says Foundation president Patty Stonesifer, a retired Microsoft executive.

"He's really touched by the people we meet, but he's also the first to draw back, to say what do we need to do to fix not just the suffering in this individual circumstance, but the system? He's not just moved by a kid story, but by the wondrous feeling you get that all these various multilateral agencies would come together to work on vaccines! For some people, that's bureaucracy. For him, that's inspiring. He loves a good system."

On a global scale, the Foundation has committed more than $3 billion to health.

Last spring, to learn more about the AIDS epidemic, the elder Gates and his second wife, Mimi, toured brothels and AIDS clinics in Africa with former President Carter and his wife Rosalynn.

The iconic snapshot from that trip pictures Nobel Laureate Nelson Mandela, Carter and Gates, each holding an African baby spared from contracting HIV by a drug that helps prevent mother-to-child transmission of the virus.

The elder Gates' thoughts when meeting the prostitutes? "I felt sorry for them," he says softly.

The babies? "I felt sorry for myself."

Apparently, Carter and Mandela, both baby-cuddling-types, immediately picked up sleepy swaddled bundles. Gates followed, but his instincts were not as keen; the infant promptly woke up and bawled. He fed the child a bottle, and was rescued by the baby's mother before having to execute a burp.

For the record, in the photograph, Three Men, Three Babies, Two Nobel Peace Prizes, all three statesmen beam.

Over the years, Gates Sr. has been a leader of King County United Way, Greater Seattle Chamber of Commerce, UW Board of Regents and two dozen other Northwest community groups. Here, he leads a committee studying the state tax system.

THE IDEA THAT some babies are born into poverty and others into privilege is central to the elder Gates' philosophy. It drives his views on philanthropy, on taxes, on public education, on what he should do with the rest of his life, on what should happen to his fortune after he's gone.

The father of the world's richest man does not subscribe to the Great Man Theory, which lionizes individuals who pull themselves up by their bootstraps.

Nobody makes it alone, he says. A person's physical comfort and opportunity have almost everything to do with the society into which he is born. Lucky if it's America; unlucky if it's Bangladesh or Botswana.

Imagine, he says.

"You'll never have a million dollars, never $100,000, never even $5,000, however smart or ambitious you are. The conditions of society don't allow for that. And you'll probably die of AIDS.

"That's the way it is. Those institutions and those phenomena of an orderly society don't exist in a vacuum. They exist because people pay taxes. If you stopped, all those things would die the next day. The police, the courts, securities markets."

Bill Gates Sr. grew up in Bremerton, the son of a furniture-store owner who had to leave school in the eighth grade but wanted his children to get a good education. After serving in the Army during World War II, Gates Sr. graduated from the University of Washington and UW law school on the GI Bill. As a child, Gates Sr. sits with his parents, left, and older sister, Merridy, on his right.

That's why the elder Gates supports the state income tax recommended by the study committee he chaired. It's why he wants the federal estate tax reformed, not repealed, a case he's detailed with co-author Chuck Collins in a new book, "Wealth and Our Commonwealth."

Critics, including Seattle Times Publisher Frank Blethen, a vocal opponent of the estate tax, say it could destroy family-run businesses such as this newspaper. "There's a misperception that this is about wealthy people," Blethen says. "I don't care about wealthy people. What I care about is jobs  preserving private companies and the jobs that go with them."

But Gates Sr. says a $3.5 million exemption before the estate tax kicks in is adequate to protect small family businesses. Citing economists' estimates, he says removing the estate tax would drain between $157 and $750 billion a year from government coffers over the next 50 years, money that's needed to build the bones of society.

The country's economic health is dependent on government-funded research, he says. The existence of Microsoft, his son's company, depends in large part on government grants that funded the Dartmouth researchers who created computer languages. Gates Sr.'s own education as an undergraduate and then law student at the UW was funded through the GI Bill after he served as an Army infantry officer during World War II.

As a member of Troop 511, Gates Sr. hiked, camped and earned merit badges with a legendary group of Boy Scouts led by his next-door neighbor Dorm Braman, who later became mayor of Seattle. Civic duty was a key theme in Troop 511. Gates Sr. achieved the rank of Eagle Scout.

"I suppose there's 100,000 examples," Gates Sr. says, "things that happened that wouldn't have happened except for government support. All this stuff is free. That's good, but if it's going to continue that way, somebody is going to have to pay taxes, and who better to pay than somebody who got rich as a beneficiary of that kind of subsidy?"

"PEOPLE KEEP ASKING me how do you raise a boy like that?" Bill's father says. "And I say, I don't have the slightest idea."

The elder Gates is equally proud of his daughters, Kristi Blake, a certified public accountant, volunteer and mother in Spokane, and Libby Armintrout, a mother of three in Laurelhurst, who serves on several volunteer boards. "They just aren't as prominent, but they're great people."

The Gates children say their parents were their models. Constant volunteering for Children's Orthopedic Hospital, Junior League, Planned Parenthood, the library, United Way. Campaigning door-to-door for school levies. Every Christmas taking the children to select and personally deliver presents and food to a low-income family.

In a short speech to accept a YMCA award for lifelong volunteer leadership, Gates Sr. choked up, as he always does when talking about matters close to his heart:

"The things each one of you is doing in the larger community today," he told his children, "are things your mother and I can only have dreamed of. I never imagined how thoroughly you would have embraced your responsibility to serve others, but then, your mother's example was stunning."

Family photos, including old portraits of his three children, Kristi, Bill and Libby, cover a wall in Gates Sr.'s home. The Gates family is very close; the elder Gates says annual family traditions, such as a Fourth of July parade with pots, pans and spoons, give children something to remember and look forward to. But he also hopes his grandchildren will look beyond themselves and their own families when considering what they'll do in the world.

Mary Maxwell Gates served on the UW Board of Regents for 18 years and eclipsed even her husband as an altruistic dynamo for her work with United Way and other charities. She came from a philanthropic family; her banker grandfather, J.W. Maxwell, helped found the Millionair Club, a Seattle employment charity.

Gates Sr. claims he doesn't know where he got his own strong sense of civic duty. Like many men who grew up during the Depression and came of age in World War II, he isn't big on navel-gazing.

"I don't know how to answer the question of why I believe anything," he says. "It's a matter of what one observes."

Gates Sr.'s grandfather, the first of four William Gateses, ran a delivery wagon in the late 1800s. When gold was discovered in Alaska, he moved his family to Nome, relocating several years later in Bremerton, where he ran a hotel and then, with a partner, a furniture store that Gates Sr.'s father eventually took over.

"Our father was a hustler, perhaps due to the fact he'd been sent out early (in the morning) to contribute to the family income, selling newspapers," wrote Gates Sr.'s sister, Merridy, in a family history. "He had to give up school in the 8th grade because he kept falling asleep at his desk. This was not especially unusual in those times, but it left him with a feeling of inferiority he never completely overcame. He had a real zeal, though, to see his son better educated than his life had permitted him."

What Gates Sr. learned best from his dad, he says, was the value of hard work, day in, day out.

The Gateses' next-door neighbors in Bremerton were Margaret and Dorm Braman and their two sons. The oldest, Jim, was young Billy's pal, and the two dreamed up games such as virtual football, which they "broadcast" from house to house, and wrote a summer weekly newspaper they financed by selling subscriptions, advertisements and 10-cent stock (which increased 50 percent in value by summer's end).

Most of all, the boys rose to Eagle rank in Troop 511, an award-winning Boy Scout troop led by Jim's father, who later became mayor of Seattle. "A lot of the fellows developed that sense of the Scout Laws: brave, loyal, clean, courteous and reverent," recalls Jim Braman. "Bill was an extreme case, of course."

After graduating from Bremerton High, Gates Sr. went to the UW for a year, did his stint in the Army, then returned to the UW, graduated from law school and married college classmate Mary Maxwell.

Elaborate handmade Christmas cards are a Gates family tradition.

The family nourished their love of games. They held an annual holiday skating party in which Gates Sr. dressed up in a Santa costume that ended at his knees. They started an annual two-week summer gathering of 11 families at a cabin camp called Cheerio on Hood Canal, featuring all sorts of ball games and races, and capped by Olympic-style award ceremonies and campfires. Gates Sr. was, of course, the "mayor" of Cheerio.

The Gateses' clever, often handmade Christmas cards became a tradition. Their dinner parties were punctuated by puzzlers or provocative questions Gates Sr. urged everyone to answer: "Who is the most influential person in your life?"

The most famous escapade was a treasure hunt dreamed up by Gates Sr. and Barbara Frederick, now executive director of Cancer Lifeline. Gates and Frederick were bridge partners in a group that has played together for more than 50 years. After four rounds held over many months, losers had to host a dinner.

The first clue was the Dewey Decimal number of a book in the public library. That led to Shuckers for a cocktail and then to a King Street Station locker filled with tennis balls and then a cup of soup at Ivar's, then an adult-entertainment parlor into which Dan Evans, then governor, dashed to claim a dildo in a heart-shaped box that contained the next clue, to a pizza place, and so on.

Evans says of his old friend, "He has a very good card sense but his bidding, like mine, is pretty erratic. He's not a conservative player. He tends to reach."

Politically independent, Gates is hard to pin down. "Early on, before Microsoft, he was certainly a moderate," Evans says. "He would have considered himself a Democrat as much as a Republican. When it comes to issues, he has strong opinions and puts his reputation and willingness to argue for a position right out front. Gun control, abortion, inheritance taxes. I admire that. I'm of the Teddy Roosevelt school . . . Pick what you believe in strongly and get out there and advocate. Don't be a fence sitter or a spectator, and Bill is certainly neither of those."

At home, he was a traditional all-day-at-the-office father of the era, businesslike in his parenting style, his children say, and yet a powerful presence in the family.

Youngest daughter Libby: "He wasn't a dad that sits and lectures or tells you how you ought to do things. . . . He listens to everything, he's never catty, he never passes judgment before he has all the facts. There's this sense of wisdom about him."

He attended her basketball games even though they were in the middle of the work day. When she was a Pomona College student and dating a guy he was concerned about, he never criticized, but instead took off work and flew to California to spend a day with the boyfriend.

"He never told me his analysis, but that was a pretty powerful thing," says Libby, who broke up with the guy for other reasons a few months later. "I realize that was an act of love. Of course, I didn't view it that way at the time."

Libby learned most about her dad when her mom was dying of cancer. "Once, my mom and I were sitting in some stark waiting room, waiting for radiation, and she said, 'Y'know, even while you're married to someone, you wonder whether they're really going to be there for you when things are hard. Now I know.' Even when she was really, really sick and there was a nurse sitting there at night, he would get in bed to be with her. He was there for her every day of her life."

The year after Mary passed away, son Bill recalls, "My dad was quiet, sullen, unusually so. He's always been a serious person, but not like that, so there was that period. After a year and a half, he met Mimi (Gardner, who'd recently moved to town to run the Seattle Art Museum), and the Foundation stuff was a fun thing for him to be doing and he got more energized."

Mimi Gardner met Bill Gates Sr. a couple months after landing in town to run the Seattle Art Museum, and they married in 1996. She calls him "a prince of a man." He delights in a new-found interest in art. They kiss goodbye twice in the morning before leaving for work.

"For all of us, it was like, you're what? You're dating? And who is this person??" Libby says. "But Mimi was amazing, and we were totally enthusiastic."

The day before his wedding to Mimi, Gates Sr. faxed his children, "I have an urge to share with you the basically happy feelings I have today as I survey my world. I am really busy and you all know what that is like, that nice tension between anxiety about producing and satisfaction in having the opportunity. . . Then, of course, there is the business of getting married. I am so comfortable and well, just happy, about the prospect of being married to Mimi. . . Not to be overlooked, the regular and permanent touch of grief about Mary and how her special kind of enthusiasm would be stimulated by all that you are doing and the good things in my life. . . Again, these are not the sort of things we say to one another very often or at all. I felt the situation was sufficiently special that it should be shared with you. Maybe some day when I'm feeling really lousy I'll send you another message."

LISTEN TO the younger Bill Gates and you get the feeling that making the world a better place is, in part, a father-son bonding project, a kind of super Pinewood Derby.

"It's fun to have something that's very complex and that engages my dad's deep abilities and experience and gets at issues that are a deep part of our lives," he says. "Growing up, we always talked about society, what's going on in the country and what we're reading about. (Working on Foundation projects), he and I have been able to talk together about broader things. . . I make sure the resources are available and he works to wisely spend the money. . . Anybody who's really exposed to the world would be doing what we're doing. That's just humanitarian instinct. "

In addition to running the Foundation, Gates Sr. is touring the country to promote his book and views on the estate tax. As a UW regent, he'll help (but not lead, he says), the search for a new president. He's also chair of the UW Foundation and its ambitious $2 billion fund-raising campaign.

"He demonstrates in himself a real work ethic and commitment to community service," says Dorothy Bullitt, executive director of Seattle Habitat for Humanity, who became friends with Gates Sr. after he read her book "Filling the Void: Six Steps from Loss to Fulfillment." "He's passed that on to his children."

For Gates, that's also the legacy to his grandchildren. "I would hope that they would be people who make a contribution beyond their own selves and their own family. To make change in the world is very rewarding. How many people have an opportunity to do that?"